Other sections of this site have demonstrated that it is a major mistake to think that deists had a clockmaker God who made the world and its laws and then withdrew from it. Their God was not remote, distant, or abstract. Nor did they lack a personal relationship with their God. Many deists believed in prayer, direct divine guidance, revelation, and miracles. The deists emphasized reason, but they saw reason as a gift from God which directed us to worshipping God and doing our duty. This means that we cannot decide someone is or is not a deist by asking whether or not he believed in revelation, miracles, immediate inspiration, or other types of active divine intervention.
There are two basic kinds of deists: those who primarily emphasized natural religion and those who primarily emphasized that the Protestant Reformation did not go far enough in its reforms. Deists who emphasized natural religion might be hostile to Christianity (like Thomas Paine), basically indifferent to it (like Ethan Allen), or sympathetic to it (like Jean-Jacques Rousseau). Deists who emphasized natural religion might go to church and consider themselves Christian too, but they will judge Christianity by how well it conforms to natural religion. They will also not agree with many if not most of the traditional Christian doctrines. Deists who emphasize the incompleteness of the Protestant Reformation generally see themselves as Christians, usually attend some church, and generally have an analysis of where Christianity made a mistake. I do not include someone as a Christian deist if he primarily emphasized denying Jesus’ total divinity and thus would be better classified as an Arian, Socinian, or Unitarian. The same point goes for someone who could be better classified as a Quaker, Dissenter, Pietist or other kind of organized group of not totally traditional Christians.
There is not widespread agreement on who can be considered a deist. I have three ways I include someone as a deist. The first way is the most obvious: the person explicitly calls himself a deist or is involved with an organization whose goal is spreading deism. The second way is for their contemporaries to call them, in published material, a deist or words with basically the same meaning such as infidel, blasphemer, or freethinker. (Freethinker is more complicated as one could be a freethinker without being a deist.) Their contemporaries took theology very seriously and they were aware of fine theological shadings we often have trouble grasping. Thinkers whose theological views were significantly different in one area or another of popular beliefs and did not fit into another category such as Quaker were called deists. The third way is to have beliefs very similar to a thinker in the first or second group.
To be included on this list it takes more than being called a deist by someone else. There has to be enough of their writings to demonstrate that they believed in basic deist beliefs. So to be a natural religion deist, they have to believe that we can know God just through natural religion. To be Christian deist, they have to declare they believed in Jesus’ message, however they understand that message, and say what true Christianity is.
Gotthold Ephraim Lessing was a famous playwright and thinker. Early in his life, he was a natural religion deist who did not see the need for further revelation. (See his essay “On the Origin of Revealed Religion.”) Later in his life, after dealing with the essays of Reimarus, he was much sympathetic to Christianity. (See his essay “The education of the human race,” and read especially paragraphs 58-100.)
Immanuel Kant (1724-1804) was Germany’s greatest philosopher. He was raised in a pious, well-off family, and eventually became a professor. He denied being a deist as he thought deists believed in a God who made the world and was then totally inactive. But with other natural religion deists, he thought God had implanted morality in us and we use this morality to judge any possible revelation from God or any religious belief or practice which claims to be from God. Many times he was very sympathetic to Christianity and other times he criticized practices and beliefs which he did not think godly. A good introduction to his ideas on religion can be found in the appendix labeled “The conflict between the theology and philosophy faculties” in The Conflict of the Faculties. This and other writings on religion can be found in Immanuel Kant, Religion and Rational Theology, trans. and ed. By Allen W. Wood and George Di Giovanni (Cambridge: Cambridge University Press, 1996).
Carl Friedrich Bahrdt (1741-1792), one of Germany’s most notorious deists, was a minister, professor, schoolteacher, and best-selling writer. He was a natural religion deist who was often sympathetic to Christianity. In English, the best introduction to his ideas is chapter 19 on his confession of faith and chapter 24 on his view of Jesus in Sten Gunnar Flygt, The Notorious Dr. Bahrdt (Nashville: Vanderbilt University Press, 1963).
Hermann Samuel Reimarus (1694-1768) studied in Holland and England before he became a professor. He wrote well-known books that did not preach the disharmony of natural and revealed religion, but after he died, Lessing published some of his private writings that advocated natural religion and were very critical of Christianity. A good introduction to his work on natural religion is Dissertation VIII “Of Providence” in The Principal Truths of natural religion defended. It is online in Eighteenth Century Collections Online. One introduction to his later anti-Christian work is his writings on miracles and prophecy in his Fragments.